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Reduce Emissions First, Reports Conclude

Geoengineering: Technology to alter Earth’s climate is not ready

by Steven Gibb
February 12, 2015 | A version of this story appeared in Volume 93, Issue 7

Credit: Shutterstock
CO2 from vehicles is a significant source of greenhouse gas emissions.
Highway crowded with vehicles with sun low on the horizon.
Credit: Shutterstock
CO2 from vehicles is a significant source of greenhouse gas emissions.

The National Research Council (NRC) is underscoring the need to reduce emissions of carbon dioxide before exploring ways to modify Earth’s climate. Altering the climate, often called geoengineering, would require significant additional research and global coordination, NRC concludes in two reports released on Feb. 10.

The first priority should be cutting greenhouse gas emissions, NRC says. Next, the possibilities for altering the climate are carbon dioxide removal (CDR) and solar radiation management (SRM), the reports say.

Both of these possibilities are hypothetical.

CDR involves several strategies. They include increasing the uptake of atmospheric CO2 by boosting photosynthesis through land management and ocean iron fertilization, burning of biomass for energy coupled with carbon capture and storage, and direct air capture of CO2. In contrast, SRM would involve injecting sulfur dioxide or other gases into the atmosphere to reflect the sun’s rays into space and thus reduce solar warming.

If more fully developed, CDR has the benefit of removing the causes of climate change and ocean acidification. In contrast, SRM would only offset the warming effects of greenhouse gases and not stem acidification from ocean uptake of atmospheric CO2, the reports say.

Methods for cutting greenhouse gas emissions are far more developed than either possibility for intervening in the climate, the NRC reports emphasize.

The NRC committee that wrote the reports urges policy-makers to first reduce emissions, next explore CDR, and only then move to examine the potential of SRM after significant research and monitoring. “The Committee considers it to be irrational and irresponsible to implement [SRM] without also pursuing emissions mitigation, carbon dioxide removal, or both.”

Pat Mooney, executive director of the ETC Group, an environmental and human rights organization, says, “The overblown and risky promise of geoengineering is the only escape hatch” left to the fossil-fuel industry.

And some NRC panelists are adamantly opposed to SRM. For instance, Raymond T. Pierrehumbert of the University of Chicago wrote in the online magazine Slate that the idea of “fixing the climate by hacking the Earth’s reflection of sunlight is wildly, utterly, howlingly barking mad.”



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